What Tottenham Hotspur left so late over in north London, Arsenal secured early way out west. The club's fastest Premier League goal proved sufficient to defeat Queens Park Rangers and ensure Arsène Wenger's side, unbeaten in eight matches but hardly convincing even against relegated opposition, are restored to third place. Their pursuit of the Champions League positions is maintained.

This team's form is relentless rather than scintillating, the visitors only imposing their quality in bursts in either half and forgiven periods of sluggish movement by QPR's all too familiar shortcomings. Arsenal were relieved to discover their hosts were as blunt as ever and, when Rangers did find some bite, Wojciech Sczcesny excelled. His diving save from Loïc Rémy's curled attempt eight minutes from time took the breath away and effectively secured the victory. What fight that had lingered in the hosts' approach, and there had been plenty to admire, was snatched from them by the Pole's fingertips.

Arsenal, with two games to play, could still be denied a top-four finish even if they register wins against Wigan and Newcastle though, with Spurs and Chelsea still to collide, chances are 73 points should prove sufficient. "I cannot even tell you what result I'd wish for in that game," said Wenger as he considered the meeting of the sides trailing in fourth and fifth place on Wednesday night. "But we have momentum. Away from home recently we have won everywhere – Fulham, Sunderland, Swansea, QPR. We are just focused on us gaining the maximum points.

"This was a difficult game for us. We needed a special focus to win here because QPR played with such quality and pride, and were fearless. You could see they had been under pressure in recent months but they are a better team than everybody expects. We played conscious of how vital the points were, so we couldn't make a mistake. That might have been a bit detrimental but we were very sound defensively and played a very intelligent game."

They benefited from the earliest gift of the Premier League season to date, Theo Walcott's winner scored virtually from the kick-off, the home defence groggy and disorganised and Arsenal pinching themselves to be confronted by such sloppiness. Laurent Koscielny's diagonal punt was optimistic but Armand Traoré, a former Arsenal player, nodded up for a scuttling Tomas Rosicky to collect on the flank. His cut-back to the edge of the area was headed down by Aaron Ramsey for Mikel Arteta, who simply slipped a pass into the space vacated by an overly eager Clint Hill for Walcott to collect and convert. Nedum Onuoha had played the forward onside to register a 20th goal of his most productive season yet.

The goal had Harry Redknapp sinking into his seat in the dugout, fretful over what might ensue. Indeed, had Rob Green not reacted smartly to turn another Walcott attempt on to a post, this might have developed into the slaughter the early strike had suggested it could become. Yet QPR, all hustle and bustle, sensed the visitors' caution and muscled their way back into contention. Park Ji-sung was wasteful before the break, Andros Townsend excellent after it with the Spurs loanee reducing Nacho Monreal to rubble on the flank. "He ran him ragged at times," Redknapp said. "People keep on about a lack of spirit but we've suffered from a lack of other stuff – goals, ability in certain areas – not spirit."

The manager is already planning for next season and, along with his first-team coach Steve Cotterill, had ventured to Selhurst Park earlier in the day with Crystal Palace's Mile Jedinak and Peterborough's Dwight Gayle assessed first hand. His more enterprising players here will surely not join him in the Championship. Townsend will return to White Hart Lane – "He's been an outstanding loan signing," said Redknapp – while Rémy, whose release clause of around £8m will surely be met by one of a clutch of suitors, had tested Szczesny before that late opportunity was saved.

That left Wenger wearing the worry lines in his technical area, cheeks puffed out and arms flapping in protest as QPR threatened or his own side's second goal proved elusive on the counter. "I waited and waited for that to come, but it never did," he said. In the end it was not needed, with the race for the top four prolonged.